A much appreciated, but perhaps not well known bus simulator has recently been released as of early March this year - Bus Simulator 16!
I purchased the game myself only a couple of days ago, but I've been hooked on it ever since. The details of the buses are amazing, and lots of different functions too! Graphics in the game aren't as good compared to games such as ETS2 and ATS but certainly still make the game enjoyable. And you don't see just endless kilometres of grass like OMSI 2 ahaha! I would recommend it, it's based on a fictional German city but they speak fluent and complete English.
Below are the key links for this game:
Website: http://www.bussimulator-game.com/index-en.php
Steam Store: http://store.steampowered.com/app/324310/
Facebook Page: https://www.facebook.com/BusSimulatorGame/